STUDIES IN PHYSICAL CULTURE AND TOURISM

Vol. 12, No. 1, 2005

The study was aimed to determine whether there was an influence of some dietary components on body weight and fat deposition in pregnant women during pregnancy and post-partum period. Measurements of skin fold thicknesses and body fat and weight were obtained from 10 pregnant women (N=10) involved in a regular exercise program throughout pregnancy, and from 10 pregnant women (N=10) who denied participation in such a program for personal reasons. During the course of the study the subjects from both groups were on a balanced diet and were supposed to make detailed records of what they were eating and drinking on a 24-hour basis for 3 days during the monitoring week every month. The results showed there was an effect of exercise in some parameters, which was not influenced by pregnancy dietary customs as they were equalized with dietary elements. The influence was more obvious in parameters concerning the period between the 3^rd and 10^th months of pregnancy.

A balanced diet is an important factor in maintaining good health in every phase of our life. Healthy diet is even more important during pregnancy because the food that the pregnant woman consumes is the basic source of important components for the fetus. The best period for a woman to start feeding herself in a healthy way is before conception, in order to ensure that she and her baby will start off with all the necessary components that will be needed during pregnancy [1]. During pregnancy it is necessary to consume nutritious components in specific amounts, according to the recommended daily consumption for pregnant women [12].

The recommended caloric consumption for pregnant women has been calculated to be 300kcal/day more than usual, in order to cover the needs of their basic metabolism that rises due to pregnancy. During pregnancy a nursing mother will need an additional 400-600 calories per day in order to cover the increased requirements of breastfeeding [4].

Pregnant women who exercise during this phase must be encouraged to follow a diet full of hydrates in order to replace the muscle glucose that has been consumed during the exercise time. Women during pregnancy usually require more proteins, iron, calcium and folic acid. Exercise can increase the needs for iron and proteins. The daily need of an exercising pregnant woman is 75g of protein, 40mg of iron and 1200mg of calcium.

A pregnant and nursing mother also needs more vitamins. An increased amount of vitamin A is more important during the postpartum period than during pregnancy because the milk, which is the only food for the fetus, must be enhanced with this vitamin. Vitamins of cluster B (niacin, B₆, B₁₂, thiamine, riboflavin) are also important in pregnancy and the postpartum period since they regulate metabolism and energy production. They are needed twice as much during pregnancy and up to 50% more during the post-partum period in which they are necessary for cell division as well as for development of hemoglobin. Shortage of folic acid may cause anemia. Furthermore, vitamin C, which helps the charge of iron and body defense, should be raised up to 70%, that is from 30-40mg/day to 60-70mg/day [10].

The aim of this study was to determine whether there was an influence of some of the dietary components on body weight and fat deposition in pregnant women in combination with exercise during pregnancy and the postpartum period.

For the purpose of the study serial measurements of body mass and skin fold thicknesses were taken from normal pregnant women with generally active lifestyles, who also engaged in regular exercise at or above a basic conditioning level for the primary purpose of health and recreation.

Of the 20 women who enrolled (N=20), 10 (N=10) formed the team that exercised during pregnancy, thus called the exercise group. The second group – the control group – included 10 women (N=10), demographically similar subjects, who did not agree to take part in the exercise program because of their concern that exercise throughout pregnancy might have negative effects on the course and outcome of their pregnancy. At the beginning of the study, 15 women formed the exercise group, but it was reduced because 5 (N=5) of them dropped out for personal reasons. Written questionnaires on subjects’ health, age, morphometry, complications and other characteristics were obtained from all members of both groups (exercise and control).

The exercise protocol, which was applied in the exercise group, included two sustained exercise sessions per week, each session lasting 75-95 minutes. Initially, the subjects started with a three-time exercise regimen per week, as it has been suggested in literature, but the pilot survey showed that this duration was impossible to be implemented in a Greek population. The exercise program was taking place at the same place, time, and using the same facilities for each subject, and each time under the supervision of experienced staff and always under a gynecologist-obstetrician’s guidance.

The exercise protocol was specified by the staff and was made uniform for all the pregnant women. In every exercise regimen, the duration, the set of exercises, and the mode and repetitions of every exercise that each woman completed or omitted were taken down. It must be noted that the subjects’ heart rate was monitored before and after the warm-up stage, as well as before and after the treadmill walk. According to the guidelines issued in 1994 by the American College of Obstetricians and Gynecologists (A.C.O.G) (1), the heart rate should not have exceeded 144 beats per minute. The exercise program started at the end of the 3^rd month of pregnancy (± 3 weeks) and was concluded just a few days before labor, for each pregnant woman. For obvious reasons it was impossible for all the subjects to be at the same state of pregnancy when they first entered the experiment.

The protocol of the study involved anthropometric measurements of body weight and height, skin fold thickness, body circumference, the percent of body fat, in addition to control of the subjects’ dietary customs, which were all performed by the end of each month. The measurement of body weight was made by accurate electronic scales, early in the morning and always in the same conditions. The body circumference was measured at 5 sites: the middle of the arm, the proximal and mid thigh, the abdomen, and the hips (with adduction of legs) in a subject in the standing position. The height was measured with a height gauge.

The skin fold thicknesses (triceps, subscapular, sacroiliacs, abdominal, thigh, midaxillary, calf) were measured by the same person using the standard LAFAYETTE skin fold caliper. Body fat was measured directly with an electrode-based body fat analyzer (Omron type).

In order to check the dietary customs of each pregnant woman, they were individually asked to write down with all details what they were eating and drinking on a 24-hour basis, for three days, during the monitoring week at the end of each month according to the data of Holland et al. [5] and Trichopoulou [11]. A total of 3 days, that is any two week days as well as one day of the weekend, were considered to be preferable for writing down the dietary custom, because of the changing rate of diet at weekends in comparison with the rest of the week. After the data had been processed a detailed analysis was carried out concerning the amount of calories per day as well as nutrients in grammars that the subjects consumed. Since it was impossible for each woman to be given a specific diet, the diet was controlled in the following way: if shortage or overuse of a nutrient was traced, a subject was provided with the appropriate guidelines in order to restore her diet program back to normal levels, always in collaboration with the consultant doctor.

The measurements took place at the end of the 3^rd, 4^th, 5^th, 6^th, 7^th, 8^th and 9^th months of pregnancy as well as at the end of the month following labor. The midaxillary skin fold was not measured in the 9^th month, because the skin was tense and technically difficult to be measured. During the week of measurements the pregnant women wrote down their diet details.

The women in the exercise group (N=10) were 28.40 ± 3.92 years of age and weighed 62.65 ± 9.19kg before pregnancy, according to their own claims. They were all generally active healthy women, with no former childbearing experience and without any previous abortions or miscarriages (Table 1).

The women in the control group (N=10) were 29.40 ± 1.78 years of age and weighed 63.00 ± 9.48kg before pregnancy, according to their own claims. They were all generally active healthy women, with no former childbearing experience and without any previous abortions or miscarriages (Table 1).

In order to evaluate differences in fat and weight as a function exercise, an effect size analysis was implemented [3, 8]. Parametric analyses were not used because of the small N size. Using Cohen’s conventions of effect sizes, a medium effect size of 0.5 was selected as representing significant group differences. Small and large effects (i.e. 0.3 and 0.8) were considered inappropriate because they represented miniscule (mainly due to random error) and large effects. The effect size analysis was carried out using formulae presented in [6, 8], in which the denominator was pooled within group standard deviation.

Firstly, descriptive statistical methods were used, which meant that the mean, standard deviation (SD) and standard error mean (SE) were calculated.

To evaluate the influence of diet on body weight and fat deposition in the pregnant women, an ‘effect size analysis’ was implemented. However, a series of covariation analysis had been initially applied so that the adjusted means could be equalized (due to the first covariates, i.e. dietary variables). The adjusted means were used later in the ‘effect size analyses’ and the subsequent effect sizes were compared to the original ones (i.e. prior to the adjustment) and only for the previously found significant effects. Effect sizes that were reduced below the cutoff 0.5 SD point were considered to be a function of the covariate.

As far as the women’s diet is concerned, Bergmann et al. [2] support the view that overweight women could follow a low-calorie diet so that they could achieve a lower rise in body weight during pregnancy, without raising the danger of giving birth to low weight infants.

Rogers et al. [7] used questionnaires with information about dietary composition and avoidance of fast food and smoking, which was filled out on the 32^nd week of pregnancy. In the study, the subjects concluded that the quality of their diet decreased during pregnancy, raising at the same time problems with avoiding overfeeding.

Suzuki and Muller [9] pointed out the need of further study that could be achieved by checking the variables of dietary customs of pregnant women. They supported the view that those elements which were related to the quality and quantity of calories consumed during the day could provide another axis of data, according to which some influences on pregnancy outcome could become obvious.

Our study concentrated on an analysis of the dietary elements of pregnant woman on a monthly basis to conclude that the influence of exercise on body weight and fat variables was solely due to exercise and not due to the diet during this phase of a pregnant woman’s life.

The conclusion of our study is that recreational physical activity has become an integral part of daily life for many women abroad especially during pregnancy, but so far not for Greek women. We believe that this is going to change in the future.

The measurements performed in this study showed that exercise during this phase of a pregnant woman’s life limited in some ways the maternal weight gain and fat deposition in women who continued the exercise program during their pregnancy as well as accelerated the reduction of pregnancy weight faster than in the subjects of the control group.